The Foreign Service Institute did a set of tapes and books for Toisanese some years ago. They also did the same for Cantonese. I speak Cantonese. Toisanese is related but not mutually intelligible. If you knew Cantonese, you could probably eventually pick up Toisanese with some effort. Since Toisanese is a language with fewer speakers than Cantonese it is common for Toisanese to be able to speak Cantonese but not the other way around. I've met lots of people from that area. Some features of Toisan include changing "t" for "h" sound. So tomorrow “ting yat-” in Cantonese becomes “hing yat” in Toisanese. Chinatown in Cantonese “Tong Yan Gai-唐人街” becomes “Hong Yan Gai”. The word for everything in Cantonese “Chun Bo-全部“ becomes “ham ba lang” in Toisanese. There is enough interaction between Toisan and Hong Kong that Hong Kong people also say “ham ba lang” but Cantonese in other locations may not know that.